add log4j to classpath in sonarqube code example

Example: add log4j to classpath in sonarqube

2019.03.19 10:51:25 INFO  app[][o.s.a.SchedulerImpl] SonarQube is stopped
FATAL StatusLogger Interrupted before Log4j Providers could be loaded.
 java.lang.InterruptedException
	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireInterruptibly(AbstractQueuedSynchronizer.java:1220)
	at java.util.concurrent.locks.ReentrantLock.lockInterruptibly(ReentrantLock.java:335)
	at org.apache.logging.log4j.util.ProviderUtil.lazyInit(ProviderUtil.java:121)
	at org.apache.logging.log4j.util.ProviderUtil.hasProviders(ProviderUtil.java:108)
	at org.apache.logging.log4j.LogManager.<clinit>(LogManager.java:89)
	at org.elasticsearch.common.logging.ESLoggerFactory.getLogger(ESLoggerFactory.java:54)
	at org.elasticsearch.common.logging.Loggers.getLogger(Loggers.java:105)
	at org.elasticsearch.common.logging.Loggers.getLogger(Loggers.java:72)
	at org.elasticsearch.common.component.AbstractComponent.<init>(AbstractComponent.java:37)
	at org.elasticsearch.plugins.PluginsService.<init>(PluginsService.java:97)
	at org.elasticsearch.client.transport.TransportClient.newPluginService(TransportClient.java:101)
	at org.elasticsearch.client.transport.TransportClient.buildTemplate(TransportClient.java:126)
	at org.elasticsearch.client.transport.TransportClient.<init>(TransportClient.java:254)
	at org.sonar.application.es.EsConnectorImpl$MinimalTransportClient.<init>(EsConnectorImpl.java:104)
	at org.sonar.application.es.EsConnectorImpl.buildTransportClient(EsConnectorImpl.java:90)
	at org.sonar.application.es.EsConnectorImpl.getTransportClient(EsConnectorImpl.java:75)
	at org.sonar.application.es.EsConnectorImpl.getClusterHealthStatus(EsConnectorImpl.java:62)
	at org.sonar.application.process.EsProcessMonitor.checkStatus(EsProcessMonitor.java:90)
	at org.sonar.application.process.EsProcessMonitor.checkOperational(EsProcessMonitor.java:75)
	at org.sonar.application.process.EsProcessMonitor.isOperational(EsProcessMonitor.java:60)
	at org.sonar.application.process.SQProcess.refreshState(SQProcess.java:161)
	at org.sonar.application.process.SQProcess$EventWatcher.run(SQProcess.java:220)
ERROR StatusLogger Log4j2 could not find a logging implementation. Please add log4j-core to the classpath. Using SimpleLogger to log to the console...